US2415901A - Pressure sensitive adhesive tape - Google Patents

Description

Patented Feb. 18, 1947 2,415,901 PRESSURE SENSITIVE ADHESIVE TAPE William L. Nelson,

, New Brunswick, & Johnson,

N. Morris Johnson Jersey Highland Park,

'and William N. J., assignors to a corporation of New No Drawing. Application September 14, 1944, Q

Serial No. 554,160

Q 2 Claims. (Cl. 117-122) This invention relates to pressure sensitive adhesives adapted for cially surgical adhesive tape.

Such adhesive tape use on adhesive tape, espeusually consists of a cloth backing and a relatively thin layer of a pres- 5 sure sensitive mass, which adheres to a that is an adhesive mass desired surface by being pressed gently against it and requires neither activation nor setting, as by heating, wetting or drying to establish the adhesion. Such pressure sensitive adhesives must be permanently tacky so asto adhere adequately to the desired surface and they must have sufllcient cohesive strength or film strength to produce the requisite bond between the surface and the cloth backing. Likewise the adhesive bond between the cloth backing and the mass must be stronger than the bond established between the mass and the surface to which the tape is applied, and the cohesiveness of the mass must be so related to these factors as to permit the tape to be unrolled without the mass adhering to back of the tape and topermit the tape the surface to which it ins adhesive on the surface.

to be pulled cleanly front is attached. without leav- It will be evident that pressure sensitive adhesives in general should have all of the quailties above enumerated.

However in adhesives for particular uses, these qualities or characteristics must be varied according to the conditions of of the surfaces to which usage and the nature' the tape is principally to be applied. In the case of surgical tape, adequate adhesion to the human skin and clean removal tial.

from the skin areessen- Likewise freedom from unpleasant odor and irritational effects are required. A white or light color of the adhesive mass is desirable. 'In addition, all these qualities must be retained over long periods of time so that the tape may remain usable after transportation and lengthy 40 storage.

Adhesives having the above characteristics to a greater or lessdegree have been long known. Rubber has generally been used as the base for pressure sensitive adhesives because it forms a tacky mass with certain-resins, plasticizers and. fillers, and the mass has desirable pressure sensitive qualities or cushion and is easily applied to suitable backings either by calendering or by mixing with. a solvent and spreading. The

pressure sensitive qualities of the mass depend upon the elastic and plastic qualities of rubber.

Rosin or rosin derivatives and coumarone-indene resins have been largely used as tackifying resins for pressure sensitive masses. Lanolin and light tainkinds of factice petroleum oils or derivatives have been largely used as plasticizers. Zinc oxide, titanium dioxide, starch'and hydrated alumina have been used as pigmenting and reinforcing and filling agents. Becaus of the marked tendency of masticated unvulcaniz'ed rubber as used in such massesto deteriorate with age, various suitable known antioxidants are customarily used to delay deterioration. However rubber base adhesives have certain limitations. They deteriorate with age in spite of the use of anti-oxidants, consequently after normal distribution and storage in readiness for use, they are frequently not usable. Moreover certain supersensitive individuals are allergic to rubber base adhesive tapes.

Our invention results from our discovery that polyvinyl normal butyl ether of high molecular weight can be modified by the addition of certo provide improved bases for pressure sensitive adhesives. The polyvinyl normal butyl ether is an elastomer, by which we mean, for the purposes of this specification, a material which, regardless of its composition, is rubbery, or has elastic and plastic characteristics similar to rubber. The polyvinyl normal butyl ether and factice provide an elastomeric base, by which we mean a base having the properties which are characteristic of elastomers. Adhesives with these synthetic elastomeric bases age better than rubber base adhesives and are less irritatingto persons having supersensitive skin. Adhesive masses based upon polyvinyl normal butyl ether alone are so tough that they are difflcult to calender to cloth tape backings by the conventional calender rolls and they do not have adequate pressure sensitive qualities. With added factice however the masses have a desirable softness and cushion resembling that of adhesives having a natural rubber base and they are easily calendered. The factice appears to act as a dispersing agent for the tackifying resin and to impart a more lasting tacky characteristic to the mass. It has been found that polyvinyl normal butyl ether having a sufficiently high molecular weight to have a plasticity between about 2.0 and about 3.5 mm. at C. in a Williams compression type plastometer is suitable for our purpose.

For the purpose of modifying the polyvinyl ether to improve the pressure sensitive and calendering characteristics of the resulting adhesive masses, we have found the following factices suitable: Amberex B, Amberex D, Amberex S and Factice 519-6, all made by Stamford Rubber Supply Company, Stamford; Connecticut. Amberex include titanium oxide to factice, tackifying resin,

oil and has an acetone extract value of about 15 per cent. Amberex S is a light colored factlce made from soy bean oil and has an acetone extract value ofv about 45 per cent. Amberex Dis 9. light colored factice made from castor oil and has an acetone extract value of about 45 per cent. Factice 519-6 is a dark factice made by the reaction of'100 parts of soy bean oil, 25 parts of Staybelite ester #10 and 28 parts of sulfur and it has an acetone extract value of about 45 per cent.

'(Staybelite ester #1015 said to be a glycerol ester or hydrogenated rosin and is sold by Hercules Powder Company, Wilmington, Delaware.)

As tackifying resin, we may use any of the resins commonly used in pressure sensitive adhesives, such as rosin or rosin derivatives and coumaroneeindene resin or derivatives such as hydrogenated coumarone-indene resins. Staybelite ester #10 is an excellent tackifier.

The softener or plasticizer may be any suitable light petroleum oil as known in the art, for example, Circo light oil, a largely alicyclic oil consisting principally of hydrocarbons containing 25 to 30 carbon atoms per molecule and one or more naphthenic or aromatic rings in the molecule, or Circosolf2XH, both made by. Sun Oil Company, Philadelphia, Pennsylvania, but we find that a particularly good plasticizer is Vistac #1, a low molecular weight polylsobutylene manufactured by Advance ,Solvents Corporation of New York. This ca'nbe mixed with small amounts of lanolin if desired. The pigment and filler may be zinc oxide, but if Factice 519-6 is used, we prefer to the extent of approximately half of the pigment content in order to avoid a brown color which this particular factice otherwise gives to the adhesive mass. Another suitable filler is hydrated alumina designated -730 by Aluminum Ore Company, East St. Louis,

- Illinois.

An anti-oxidant must be used which does not irritate-the skin and which does not discolor either the cloth backing or the adhesive mass, a suitable one being an alkylated polyhydroxy phenol known as Santovar 0, made by Monsanto Chemical Company, St. Louis, Missouri.

In making adhesive tape embodying our invention we prepare an adhesive mass by mixing together on any conventional rubber mill the desired proportions of polyvinyl normal butylgether,

softener or plasticlzer, filler and anti-oxidant and spread this on suitable cloth backing with the conventional calender. We have found that a suitable elastomeric base is provided when the polyvinyl normal butyl ether constitutes between about 62 per cent and about 85 per cent of the base, the remainder being factice which varies accordingly from about 38 per cent to about 15 per cent. When so used the polyvinyl normal butyl ether constitutes preferably between about 18 and about 30 per cent of the entire mass and factice constitutes between about 5 and 13 per cent. Preferably the proportions of the remaining constituents are tackifying resins from 20120 35 per cent, softener from 5 to 20 per cent and filler from 20 to 35 per cent.

.heslves embodying our invention are the following, the percentages being by weight.

Example 1 Percent Polyvinyl normal butyl ether 25 Amberex S 10 Stabellte ester 10 (Hercules) 30 Circo light oil 6 Zinc oxide 18 Titanium oxide 10 Santovar O 1 Example 2 Percent Polyvinyl normal butyl ether 20 Amberex B- 10 Staybelite ester #10 (Hercules) 30 Circo light oil 8 Zinc oxid 31 Santovar O 1 Example 3 Percent Polyvinyl normal butyl ether 25 Factice 519-6 10 Staybelite ester #10 (Hercules) 30 Vistac 6 Lanolin 2 0-730 (hydrated alumina) 11 Titanium oxide l5 Santovar 0 1 We claim:

1. In an adhesive tape a pressure sensitive adhesive mass comprising an elastomeric base consisting of polyvinyl normal butyl ether from about 62 per cent to about per cent and iactice from about 38 per cent to about 15 per cent.

2. In an adhesive tape a pressure sensitive adhesive mass comprising an elastomeric base, a tackifler, a plasticizer, a filler and an anti-oxidant, the elastomer consisting of polyvinyl normal butyl other from about 62 per cent to about 85 per cent and faotice from about 38 per cent to about 15 per cent.

- WILLIAM L. NELSON.

WILLIAM N. MORRIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,061,934 Mueller-Cunradi Nov. 24, 1936 FOREIGN PATENTS Number Country Date 414,699 British Aug. 7, 1934 OTHER REFERENCES Industrial and Eng. Chem., article by Fisher, pp. 941-945, vol. 31, No. 8, Aug. 1939. (Copy in Div. 50.)